There seem to be varying views expressed here, as I've been reading many previous posts as a new member.

My new speakers (cherry finish, passives) are not arriving for about three weeks, so I'd be interested in others experiences. I find it easier to understand transducers loosening up, than cables and electronics, but I know some believe everything needs 'running in'. Or is it just our senses acclimatising?

We had our original demo pair of curved SCM40 passive monitors for over three years and I didn't hear a change in their presentation.

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Rick @ Musicraft

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In my experience, the overall ATC sound remains the same but I did find that after about 100+ hours the bass got bigger and more impressive with all my ATCs (SCM 20A Pro, SCM 100A and my current EL 150A)!

MevDinc wrote:In my experience, the overall ATC sound remains the same but I did find that after about 100+ hours the bass got bigger and more impressive with all my ATCs (SCM 20A Pro, SCM 100A and my current EL 150A)!

Thanks, MevDinc. That's more the typical audiophile experience, and what I've seen in old threads here and on other fora. It's usually bass getting fuller or treble becoming less grainy/gritty. I remember my last speakers seemed quite bright at first, but that was almost 20 years ago, so it's a distant memory!

With a bit of basic physics I can see that even the difference between moving speakers from a cold warehouse/stock room and them operating in a warm living room might make a bit of difference. Equally, I'm sure our brains adjust what we hear when using components with a different balance. Just as an instrument sounds different in a different hall, we don't usually think "That clarinet sounds like an oboe", for example.

As Nopiano, I think room temperature can make a difference. In a colder room I'd say my 50s like a bit of time to get going.

But without doing a fast A/B no-one can be sure either way. Of all the discussions and reviews mentioning warm up, I know of only ONE where they listened to hot and cold units with fast A/B (SOS review of DAC1).

As for break in, I'm more skeptical about this being a significant, common issue.

When I visited the ATC factory they showed me how they test all drive units. Part of the test is subjecting the drive unit to a very high-level sine signal causing extreme excursion for a period of time to physically expose any irregularities in assembly e.g. coil misalignment in the magnetic gap or any loose seams. This stresses the driver well beyond anything that can be achieved under normal operating conditions so makes discussion of any further driver loosening up irrelevant.

First, I've never had a customer say a replacement driver "sounded different" (woofers or midranges). How is that possible if break in is a fact? A 5-10 year old driver does not sound different from a brand new one? That would be contradictory to the break in idea. Second, how does the driver know to stop "loosening up" or "settling in" ? If its a compliance issue, how does it know to stop? It would make sense if a driver changes over time in use, it would continue to change in use. And if one wants to make the argument well they reach a point and then stop, how would it be that all drivers reach exactly the same point and stop "breaking in" exactly the same way? the break in argument seems to lead to old drivers sound different than new ones but I have yet to have that comment from any customer- ever!

Now in the case of ferrofluid tweeters, that is true, they do change over time. But its slow and even every day all day studio users don't even hear the change, they just know after a year of use its time for new ones. They sure do notice a difference on that driver change though! This is one of the best things about the new ATC tweeter: no Ferro Fluid.

I think Alex's explanation is the only one that makes the most sense to me- its "us", our own ears that are breaking in to a sound. And Darren's comment about temperature of the room/air is interesting too. I know there is some science behind that idea. Heck maybe someday they will find out its barometric pressure that affects our ears and perception!

With non ATC speakers, power compression is a real thing and this does change the speaker in use as it heats up. The coils get too hot and the speaker begins to loose dynamics and response, distortion rises. This is a very real thing in studios, with a speaker on LOUD for 12 hours. This is why many in the recording business are shocked at how different their mix sounds in the morning vs when they left last night after a long day. Fortunately this is not an issue wth ATC, I have many recording users who own ATC for this specific reason.

Thank you for the further thoughts, and I've not looked in since the weekend because my new toys arrived a week earlier than expected, so I've been listening not reading!

The experience of all units being tested to the extreme during manufacturing would indeed seem to me to overcome the usual expectation that some sort of breaking in might occur at home. I'm sure many manufacturers don't test all units like this, and even giving the final product a quick blast of music or sound might beyond mass production in some cases.

I found a review reprint of the SCM11 on the ATC website which suggested this model sounded better at around 22 Celsius, than 19C. Fortunately, we've been enjoying a warm spell! I'll bear this in mind in the winter months, however.

For what it's worth, I heard nothing when first playing my new models that suggested they weren't operating exactly as intended, and were as close to the well-used demo pair I had borrowed as my aging ears could detect. I have heard new speakers sound a but scratchy and 'tight' but not these. Obviously I can't yet know if they will yet evolve in some way, but as others have said, such things are more likely to be my own ears or perceptions than anything more dependable.